Lab Exam Help

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Published on 9 Oct 2011
School
UTSC
Department
Chemistry
Course
CHMB41H3
Professor
CHMB41H_Laboratory Test Preparation Guidelines
The following list is a guideline/summary to help you prepare for your lab test. The test is 90
minutes for both practical and written section. Approximately half of the test is the practical
technique and the rest is theory/written questions.
1. You will be tested on one of 5 techniques you have performed this semester: Distillation,
Extraction, Recrystalization, Reflux or Solubility/Solvent.
2. You will be graded on HOW you perform the techniques, according to what you have
been taught in the lab and seen on the videos (so not just on the final product/result
handed in). Please watch the lab videos and lab seminar handouts posted to review the
techniques and apparatus use/setup (i.e. m.p. machine, refractometer, etc) before the lab
test. You should also check the appendix section for definitions and further details on the
techniques.
3. You should know how to calculate percent compositions, theoretical yields and any other
forms of calculation you did for your pre-lab and/or on your data sheets.
4. You should NOT memorize amounts of reagents as this will be given to you if needed.
Most important of all is that you UNDERSTAND (and not memorize!) why you did
certain steps or used certain reagents, techniques, etc instead of other options (i.e gravity
filtration vs. suction filtration, why you cooled or heated something, why you used one
solvent and not another, why water flows in a particular direction in a condenser)
5. Review answers to lab manual questions as they may come up again on your lab test
6. Know reactions that pertain to theory of the experiments you did (e.g. reaction of t-butyl
chloride synthesis)
7. Understand and be able to draw a % composition/temperature graph for distillation of a
two-component mixture.
8. Understand (and NOT memorize!) the solubility chart and what each solvent helps you
identify (i.e NaOH vs NaHCO3 distinguishes between strong and weak acids like
carboxylic acids and phenols, acids identify basic functional groups, ether and water
distinguish between organic molecules and ionic compounds, etc)
9. Understand what color changes occur on litmus paper, Congo red paper and universal pH
paper under acidic and basic conditions.
10. Know techniques used for troubleshooting or outcomes if a setup is not correct (i.e. what
to do if something doesn’t recrystalize? How to tell layers of separation apart in an
extraction? What happens if thermometer position not correct in distillation? Etc…)
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Document Summary

The following list is a guideline/summary to help you prepare for your lab test. The test is 90 minutes for both practical and written section. Approximately half of the test is the practical technique and the rest is theory/written questions: you will be tested on one of 5 techniques you have performed this semester: distillation, Please watch the lab videos and lab seminar handouts posted to review the techniques and apparatus use/setup (i. e. m. p. machine, refractometer, etc) before the lab test.